https://standardnotes.org/Your notes are encrypted and secured so only you can decrypt them. No one but you can read your notes (not even us).
I spent some time testing this program because of it's compatibility with AlephNote and after I had issues with the SimpleNote service. While I maintain high hopes for the program and appreciate very much what they're trying to do, I found it didn't work out with my setup. The client couldn't handle basic formatting needs and the versioning system really wasn't adequate. It overwrote some important info with the wrong version, and had no option to go back and look at available or conflicting edits.
Status: Untested. It's Electron-based and probably not portable -- go for the AlephNote client instead. Also, whatever else I like about this program it's a 101 meg download for a simple note program, which is madness.
Anyway, the search for a good notes service continues, but if anyone's curious, my current notes program is Zoho Notepad (https://www.zoho.com/notebook/). It's far from perfect (recommend using the web interface, skip the app download), but so far hasn't lost any of my data and seems to have good security/privacy.